There are many environments where enhancing worker safety is desirable. Examples of such environments include loading dock areas, warehouses, distribution centers, and similar facilities. In addition to such places usually being crowded, noisy and full of activity and other distractions, the juxtaposition of people and vehicles (fork trucks, pallet jacks, etc.) greatly increases the potential dangers. People and heavy, moving vehicles do not consistently interact this way in other environments (e.g. on the street with defined lanes/roads for vehicles, sidewalks and crosswalks for pedestrians, stop signs, stoplights, etc.), but it is currently the status quo in the enumerated environments. As a result, accidents in which individuals are struck by forktrucks, and similar and related accidents, are all too common.
Several factors can increase the likelihood of such accidents occurring. One factor is the crowded, busy, noisy, distracting environment referred to above. The presence of such distractions can prevent an endangered individual from realizing and reacting to a dangerous situation. Ironically, one source of such distractions are the myriad lights, strobes, horns and/or buzzers intended to warn against such dangers. Another factor is the presence of blind spots. An individual walking down an aisle in such a facility is not able to see potential dangers around the corner at the end of the aisle, or at a mid-aisle break. The way forktrucks are used to load and unload trucks parked at a loading dock also create blind spots for a driver of the forktruck. Typically, a fork truck is driven forward into a trailer, and then driven in reverse to depart the trailer. While swiveling seats and/or fork truck mounted mirrors are used in attempts to minimize this problem, these attempted solutions are not completely satisfactory. Indeed, an individual that spends any significant amount of time in such a facility typically adopts the practice of stopping and looking into each trailer parked at a loading dock as he traverses from dock to dock—for fear of being struck by an inattentive or blind-spotted backing fork truck.
The current mechanisms for preventing or minimizing the severity of these kinds of accidents generally fall into two categories. The first category is personal safety items—typically some sort of apparel. Common examples include hard hats, safety glasses, steel-toed shoes or boots and safety vests. Most of these apparel items are intended to minimize the effect of such an accident. A hard hat, for example, can cushion but not prevent a blow to the head. Some safety vests are intended to help in preventing accidents, as they can be made of highly reflective or brightly-colored fluorescent material to increase the visibility of the wearer so they can be seen by a fork truck driver or other source of hazard. In general, these safety items are limited in their effectiveness in that they are passive. On the other hand, they do provide the benefit of being worn by and traveling with the person being protected.
Besides such personal safety or apparel items, the other category of devices intended to prevent or minimize these kinds of industrial accidents are warning systems. Typically, some kind of warning/signaling device (a red light, a flashing light, a strobe light, a horn, a bell, a buzzer, etc.) is activated in response to the detection or sensing of a dangerous condition. Such sensor-responsive signaling may include a light being illuminated when a piece of equipment is turned on. Other signaling might be activated by the detection or sensing of a dangerous operational condition of a piece of equipment, such as the signaling of movement of a piece of equipment representing a hazard (e.g. a backup beeper for forktrucks). Another example loading dock safety device known as a vehicle restraint is intended to engage the Rear Impact Guard (RIG) of a trailer parked and being un/loaded at the loading dock to prevent the dangerous condition of the trailer departing from the dock while being un/loaded. In such loading dock safety devices, a sensing mechanism is employed in an attempt to determine if the RIG had indeed been captured by the restraint. If so, a light inside the dock is illuminated green to indicate that the trailer is restrained and can be safely un/loaded. If, however, the sensor does not detect capture of the RIG, and inside red warning light is illuminated and/or a horn sounds to signal that it is unsafe to un/load the trailer. Other forms of vehicle restraints are designed to engage other structure on the vehicle such as the wheels, the chassis, the bogey rail, etc.
Systems also exist to attempt to warn either pedestrians or proximate fork trucks of imminent collisions between the two. While a variety of sensing technologies have been coupled with warning signaling, such systems do not fully or effectively address the situation. For example, the warnings they provide may suffer from a lack of specificity. This lack of specificity may be in regard to what the hazard is. A given facility can have so many lights, horns and sirens that it may be difficult for an endangered individual to properly associate a given warning with a given threat. The lack of specificity may also relate to who is in danger. If, for example, a sensing system is intended to detect when a person has entered into a large, designated area, several people in close proximity to the area may hear or see a warning and may all be under apprehension of danger based on that warning signal, even though only one of them has actually breached the area. Given this example, a more likely result is that all of the individuals will ignore the warning as it is unable to specify who is in danger. The lack of specificity may also apply to the location, direction, or distance (in either physical distance or temporal distance) of the impending hazard. Relatedly, the timing of the hazard may be imprecisely conveyed by the warning used—with the endangered individual not knowing if there is a generalized threat that may occur at any time, or if a given threatened harm is imminent. This unduly limits the opportunity for the threatened individual to take appropriate avoiding or remedial action relative to the threat. Additionally, an imprecise and/or constant apprehension of danger may result in the loss of productivity of the affected personnel.